Efficient and Stable Inverted Planar Perovskite Solar Cells Using a Triphenylamine Hole‐Transporting Material

Inverted perovskite solar cells (PSCs) with a p‐i‐n structure have attracted great attention. Normally, inorganic p‐type metal oxides or polymers are used as the hole‐transport material (HTM), a vital component in the inverted PSCs. However, this type of HTM often requires high processing temperatures and/or high costs. On the other hand, a commonly used organic HTM, poly(3,4‐ethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS), is sensitive to humidity and thus affects the stability of the PSCs. Herein, we employ a small molecule, 4,4′,4′′‐tris( N ‐3‐methylphenyl‐ N ‐phenylamino) triphenylamine ( m ‐MTDATA) to replace PEDOT:PSS as a new HTM for inverted PSCs. Compared to a PEDOT:PSS‐based device, m ‐MTDATA‐based PSCs exhibit enhanced performance. The highest power conversion efficiency (PCE) was notably improved from 13.44 % (PEDOT:PSS) to 18.12 % ( m ‐MTDATA), suggesting that m ‐MTDATA could be an efficient HTM to achieve high performance inverted PSCs. Furthermore, the m ‐MTDATA‐based device demonstrated improved stability (retaining 90 % PCE) under ambient conditions over 1000 h compared with the PEDOT:PSS‐based devices (retaining 40 % PCE).